Call screening at a hierarchical switch based on organizational membership of the parties

ABSTRACT

A telecommunication network has first and second subscribers connected to first and second telecommunication switches, respectively. A third switch is disposed at a hierarchical level above the second switch and receives a call setup message. The call setup message includes a first group affiliation parameter defining one organization of which the first subscriber is a member and a destination number of the second subscriber called by the first subscriber. A record in a database coupled to the third switch is located in response to receiving the call setup message. The located record is based on the destination number contained in the call setup message. A call screening parameter stored in the record is also identified. A determination is made of whether the call will be allowed to terminate to the second subscriber based on a comparison of the call screening parameter and the first group affiliation parameter. Thus, call screening is based on the membership of the first subscriber in an organization.

BACKGROUND OF THE INVENTION

This invention is directed to a telecommunication network in which callscreening is made based on organizational membership of the calling orcalled parties by a hierarchical switch at a hierarchical level abovethe originating and terminating switches for the call.

A telecommunication switch which supports Centrex services provides callorigination screening for outbound calls of subscribers connected to theCentrex service. For example, certain subscribers, i.e. subscriberlines, may be unrestricted in outgoing calling privileges while othersubscriber lines may be limited to only placing calls to othersubscribers of the Centrex service. Such a call screening mechanismoperates on the call origination switch and applies a predetermined setof parameters to determine whether a requested outbound call ispermitted for the subscriber line originating the call request. Such asystem is effective in limiting outbound calls based on parametersavailable at the origination switch. Other systems permit call screeningto be made by the terminating switch. A need exists for an improved callscreening technique which provides greater flexibility with regard tothe screening of calls based on characteristics associated withindividual called parties.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a solution to this needwherein an improved technique permits call screening to be implementedbased on characteristics, other than directory number, associated withan individual called party.

In accordance with an illustrative method of the present invention, atelecommunication network has first and second subscribers connected tofirst and second telecommunication switches, respectively. At a thirdswitch disposed at a hierarchical level above the second switch, a callsetup message is received from a fourth switch disposed at ahierarchical level above the first switch. The call setup messageincludes a first group affiliation parameter defining one organizationof which the first subscriber is a member, a destination number of thesecond subscriber called by the first subscriber, and a hierarchyparameter identifying that services are being provided by the third andfourth switches. The first group affiliation parameter is based on arecord retrieved from a database coupled to the fourth switch. A recordin a database coupled to the third switch is located in response toreceiving the call setup message. The located record is based on thedestination number contained in the call setup message. A call screeningparameter stored in said record is also identified. A determination ismade of whether the call will be allowed to terminate to the secondswitch based on a comparison of the call screening parameter and thefirst group affiliation parameter. Thus, call screening is based on themembership of the first subscriber in an organization.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram of a telecommunication network whichincorporates an embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a telecommunication network in which local access andtransport areas (LATA) support communications among subscribers locatedin the LATAs. Communications between the LATAs are provided by switchesassociated with the toll switching system. The LATA 10 which may belocated in the Chicago, Ill. area serves a plurality of subscribersincluding a business subscriber associated with customer premisesequipment (CPE) 12 which may typically consist of a telephone set.However, it will be understood that CPE may consist of various equipmentsuited for the transmission of data as well as voice communications. TheCPE 12 is directly supported by a private branch exchange (PBX) 14 whichmay comprise an AT&T PBX such as the Definity. The PBX 14 supports aplurality of CPE equipment (not shown) directly coupled to the PBX. Acentral office switch 16 such as an AT&T 5ESS® switch supportscommunications from the business subscribers associated with PBX 14 viatrunk lines 18 connected between the PBX and the switch. It will beunderstood that other subscribers can also be directly served by switch16.

Additional subscribers, for example the subscriber associated with CPE20, within LATA 10 are supported by central office switch 22. Thesubscriber associated with CPE 20 may be a residential telephone user ora general member of the public served by a telephone. Another class ofsubscribers, e.g. a business user associated with CPE 24, are supportedby Centrex service equipment 26 associated with central office switch22. These subscribers typically represent groups of business customersor other groups which desire common calling features among relatedmembers which are supported by Centrex services. Although, subscribersserved by a PBX or Centrex services may be provided with similarfeatures and capabilities, differences in the implementation of suchservices often limits the use of the features to other members directlyserved by the same PBX/Centrex equipment. Switches 16 and 22 maycomprise program controlled switches such as the AT&T 5ESS Switch.

An inter-exchange carrier (IXC) switch 28 supports communications withcentral office switch 16 by trunk lines 30 and central office 22 viatrunk lines 32. An inter-exchange carrier provides what is commonlyreferred to as long distance service and may consist of a carrier suchas AT&T Corp. Such carriers provide interLATA communication services.The IXC switch, which may comprise an AT&T 5ESS switch, functions as anedge or point of contact switch with communications from LATA 10. Itwill be understood by those skilled in the art that switches 16 and 22will also have trunk communication channels with other intraLATA andinterLATA switches. A service control point (SCP) database 34 is coupledto switch 28 by communication lines 36. In accordance with an embodimentof the present invention, the SCP 34 stores a plurality of recordscorresponding to subscribers served by LATA 10. The records containindividual subscriber data relating to call features and could containthe type of CPE used.

Toll switches 38 and 40 provide backbone interLATA communicationservices between a LATA and another LATA or a foreign telecommunicationjurisdiction. Telecommunication trunk lines 42 provide communications(customer data and telecommunication signaling) between switch 28 andswitch 38; trunk lines 44 provide communications between toll switches38 and 40. Trunk lines 46 connect toll switch 40 and another IXC switch48. An SCP database 50 is connected to switch 48 by communicationchannels 52. The SCP database 50 stores records associated withsubscribers within LATA 54.

The LATA 54 includes a central office switch 56 which is connected bytrunk communication lines 58 with IXC switch 48. The switch 56, whichmay comprise an AT&T 5ESS switch, provides direct subscriber services toresidential subscribers, for example a subscriber associated with CPE60. The switch 56 also provides Centrex services 62 to subscribers, suchas the subscriber associated with CPE 64. Central office switch 66 isconnected by trunk communication lines 68 with IXC switch 48. PBX 70 isconnected by trunk communication lines 72 to switch 66 and supportssubscribers such as a business subscriber associated with CPE 74.Switches 56 and 66 are similar to switches 22 and 16. Groups ofaffiliated business subscribers may be supported by the Centrex or PBXfacilities.

The network shown in FIG. 1 is simplified in order to more clearlyillustrate the embodiments of the invention. It will be apparent tothose skilled in the art that other non-illustrated elements are presentand operate to perform known functions. For example, signal transferpoints (STPs) are used to transmit data and command information amongthe switches and databases (SCPs) using data transmission links as isknown in signaling system 7. In a high reliability network the STPs andSCPs are deployed in duplicate pairs so that one pair is available inthe case the other pair becomes unavailable such as during an unexpectedfailure or while maintenance is being performed. The shown communicationtrunk lines between switches are actually two sets of communicationlinks: one for user information such as voice and the other for thetransmission of control messages and data between the switches. Notshown are STPs associated with each switch and database; the STPsfacilitate the communication of the control data on the separate links.

In accordance with the present invention IXC switch 28 is capable ofproviding a point of access interaction by trunk lines 30 and 32 tosubscribers served directly or indirectly by central office switches 16and 22. Similarly, IXC switch 48 provides by trunk lines 58 and 68, apoint of access interaction with subscribers served directly orindirectly by central office switches 56 and 66. "Point of access"capability of the IXC switches means that these switches have thecapability of servicing incoming call requests like a local centraloffice switch. Further details describing the utilization of thiscapability to provide features in accordance with the present inventionare described below with regard to examples of call handling by thenetwork.

As shown in FIG. 1, SCP databases 34 and 50 contain records relating toindividual subscribers served by LATAs 10 and 54, respectively. Table 1illustrates exemplary records stored in these SCP databases. The recordsassociated with CPE 60, 64 and 74 are stored in SCP database 50; theother exemplary records shown in Table 1 are stored in SCP database 34.Each record includes data defining features and CPE type. The recordidentified with subscriber "PIN(X)" indicates a record identified solelyby a personal identification number X as opposed to the other subscriberrecords shown in Table 1 which are associated with specific CPEs.

Referring to Table 1, a record exists for subscriber 24 which includesdata that has predefined features and CPE type. It will be understoodthat subscribers identified by reference numbers are subscribersassociated with the CPE of the same reference number. Typically, recordsstored in SCP database 34 are located by reference to a predetermineddirectory number assigned to the subscriber. It will be well known tothose skilled in the art that the calling party's directory number canbe automatically generated by the supporting central office switch andforwarded to the IXC switch with the call initiation request, such as byutilizing the known signaling system 7 (SS7). This permits the IXCswitch to locate the corresponding record in the SCP database.

Referring to Table 1, subscriber 24 has a stored directory number of312-713-1234 and a predetermined set of features. One feature includesan individualized dial plan (IDP1), also known in telephony as a customor customized dial plan. The IDP1 defines a business group (BG) dialplan utilized in making business calls and abbreviated called dialinginformation such as the prefixes, if any, and number of digitsassociated with extension-only dialing of another business groupsubscriber. For example, the IDP1 may define that a five digit numberconstitutes a BG extension if a predetermined leading digit(s) is used.

Another group of features is associated with terminal group and stationrestrictions (TGSR). The illustrative TGSR features include thedefinition of a terminal group identification (TGID) of 05 (anintraswitch identification of business group), and further definesbusiness group restrictions associated with subscriber 24 as being asemi-restricted originating (SRO) and unrestricted terminating (URT)permissions. A semi-restricted originating permission restricts thedirectory numbers which can be called by the subscriber. For example, asubscriber may be limited to directory numbers associated only with hisbusiness group or company or to a predetermined local group of directorynumbers, so as to restrict toll dialing. With regard to receiving orterminating a call, subscriber 24 is designated as an unrestrictedterminating permission indicating that this subscriber can receive allcalls without restriction, that is, without limitations.

A multi-switch business group (MBG) feature includes an identificationnumber (MBGID), e.g. an MBGID of 10. This identification can be usedacross switches to classify related groups of subscribers such asmembers of the same company which can be used for call control purposes.The CPE type of subscriber 24 is defined as analog with dual-tonemultifrequency (DTMF) signaling capability. This defines the type of CPEequipment associated with the stored directory number of subscriber 24.In view of this illustrative set of features for subscriber 24, it willbe apparent that some forms of signaling typically utilized from a CPEto a supporting switch is not utilized by any of the defined features.For example, a flash-hook signal is not needed to activate any featureassociated with subscriber 24, and hence would not be recognized by IXCswitch 28. However, a flash-hook signal may be recognized by theintermediate central office switch 22 or the related Centrex equipment26 which are also capable of serving subscriber 24.

The record associated with subscriber 12 as shown in Table 1 is similarto the record associated with subscriber 24. Differences between therecords include a different directory number, a different terminal groupidentification (06 rather than 05) and an unrestricted origination (URO)restriction as opposed to a semi-restricted origination (SRO)restriction for subscriber 24. The unrestricted origination indicatesthat subscriber 12 has no restrictions on the calls which can be made,i.e. any directory number can be dialed and processed as a valid callrequest. An SRO restriction would limit the subscriber to calloriginations to only members of the same BG. It will be noted thatsubscriber 12 has the same MBGID(10) indicating a common organization orcompany affiliation with subscriber 24. The CPE type for subscriber 12is a custom integrated services digital network (ISDN) terminal.

Subscriber 20 has a null entry for features, indicating that thissubscriber is to be treated as a plain old telephone service (POTS) typeof service. The CPE type is defined as an analog DTMF terminal. Theanalog CPE type indicates that analog signaling can be originated andreceived as opposed to the ISDN CPE type associated with subscriber 12which uses digital signaling using the data or D-channel associated withISDN lines. Alternatively, no entry (record) for subscriber 20 would berequired if a default condition of POTS is assumed for subscriberswithout records.

A subscriber identified as PIN(X) has a record stored in SCP database 34but is not associated with a predetermined CPE. The PIN(X) subscriberrecord is retrieved by a caller entering a personal identificationnumber from any CPE. The features associated with this subscriber aregenerally similar to the features described with regard to subscriber12, but does not contain a terminal group identification parameter.However, the PIN(X) subscriber includes an additional feature of "3-WAY"indicating that this subscriber is allowed to make 3-way calls. Since aflash-hook signal, or the equivalent of the flash-hook signal ifimplemented in ISDN signaling, is utilized for 3-way call signaling, aflash-hook signal will have meaning to and be acted upon by IXC switch28 during a call involving the PIN(X) subscriber. The CPE type isindicated as "NULL" since the type of CPE equipment which may beutilized by the subscriber is not known.

Table 1 is an example of certain records stored within SCP database 34in accordance with the present invention. Likewise, stored within thisdatabase will be subscriber records associated with features and CPEtypes for other CPE associated subscribers and PIN identifiedsubscribers within LATA 10.

As shown in Table 1, subscribers 60 and 64 include similar features andCPE definitions as described above. However, it will be noted that thesesubscribers are supported by IXC switch 48 and hence, their records arestored in the associated SCP database 50. These records are shown inTable 1 for convenience and to enable comparisons to be easily made. Thefeatures associated with subscriber 64 are similar to that previouslydescribed for subscriber 24 except that the terminal groupidentification for subscriber 64 is 15 (as opposed to 5 for subscriber24). It will be further noted that the CPE type for subscriber 64 is anational ISDN (N-ISDN) terminal type. It will be noted that subscribers12, 24, 64, and PIN(X) are members of the same multiple switch businessgroup as indicated by the same MBGID identification.

In accordance with the embodiments of the present invention, the IXCswitch provides features and services that traditionally are provided bya PBX, Centrex, or central office which directly serves the subscribers.Groups of subscribers, such as geographically separated groups ofemployees of the same corporation, which are served by different PBXs,Centrex equipment, or central offices in different LATAs, can be treatedas a common business group for purposes of communication services, andcan be provided access to the same dialing plan, features, and services.This constitutes an advantage in that it makes the operation of thetelephone services seem the same for the different groups ofsubscribers.

Call Scenario #1

In this example subscriber 24 makes a call to subscriber 12. The IXCswitch 28 provides primary handling of the call even though neither theoriginating subscriber 24 nor the terminating subscriber 12 aresupported directly by switch 28. Since IXC switch 28 provides theprimary call processing, enhanced subscriber features can be supported,such as on-network (abbreviated) dialing, even though subscriber 24 issupported by Centrex 26 and subscriber 12 is supported by PBX 14. Itwill be noted by those skilled in the art that in a conventional systema subscriber supported by Centrex features of a central office switchwould not be able to utilize Centrex features such as on-network(abbreviated) dialing except with other subscribers supported by thesame Centrex facility. It is similarly true that subscriberstraditionally served by a PBX could not utilize such features exceptwith other subscribers supported by the same PBX.

Subscriber 24 goes off-hook and receives dial tone via Centrex 26 andcentral office switch 22. In this illustrative example, subscriber 24then dials an access code followed by the abbreviated number fordestination subscriber 12. Trunk 32 could be a trunk sharing publictraffic (public trunk) or it could be a private dedicated trunk (privatetrunk). Call processing is discussed for each of these two types oftrunks.

Assume in a first example that trunk 32 is a public trunk. Subscriber 24dials an access code, such as *10288, followed by the abbreviated digitsfor the called party. The access code digits "*10" inform switch 22 thatan alternate carrier is being requested to provide services to thesubscriber. The access code digits "288" inform switch 22 that thealternate carrier to provide the services is AT&T. In response to thereceipt of the access code, switch 22 will route the call over trunk 32and provide signaling to switch 28 via trunk 32 requesting that switch28 provide primary call origination services. This signaling which willbe communicated on trunk 32 can be in the form of a network specificfacility (NSF) parameter within the signaling system 7 (SS7) call setupmessage. It will be understood by those skilled in the art that althoughthe SS7 signaling is utilized in this example, other types of signalingwhich can convey this request to switch 28 can be utilized. The NSFparameter will convey to switch 28 that the call request is for primarycall origination services and that the provider of the services is to be288, i.e. AT&T. Switch 28 then queries SCP 34 database with parameterinformation designating AT&T as the service provider, as well asincluding the calling party number, also known as automatic numberidentification (ANI), abbreviated called digits, and any other necessaryinformation for the query.

In a second example, trunk 32 is a private trunk. Suppose trunk 32 is adedicated trunk used only for traffic from local subscribers whosubscribe to AT&T for their local service. (AT&T is one of the IXCswitch 28 providers of primary call origination (e.g. local) services.)Then IXC switch 28 when receiving a call over trunk 32 will know theoriginator to be an AT&T service subscriber and to query the SCP 34database with parameter information designating AT&T as the serviceprovider. Again, any other necessary information will be included in theSCP query, such as the calling party number and the abbreviated calleddigits.

In this case, subscriber 24 may dial an access code, such as "*8",followed by the abbreviated digits for the called party. Note that the*8 could be automatically generated or prefixed by the Centrex 26 customdial plan, and thus does not necessarily have to be dialed by subscriber24. If "*8" is automatically transmitted, subscriber 24 just dials theabbreviated digits for subscriber 12. The access code "*8" serves tocause Centrex 26 and central office switch 22 to route the call overtrunk 32. Since trunk 32 is dedicated, IXC switch 28 will havepredetermined instructions on how to handle the call as described above.

The IXC switch 28 retrieves the records associated with subscribers 24and 12, compares the MBGID of subscribers 24 and 12, and determines thatboth the calling and called party are members of the same businessgroup, namely, MBGID=10. In accordance with the illustrative example,calling party 24 is permitted to only make calls via switch 28 tomembers of its MBG since it has a semi-restricted origination (SRO)parameter. Since subscriber 12 is a member of the same MBG, the callorigination screening by IXC switch 28 is satisfied. The switch 28 alsoconducts a call termination screening using the "₋₋ RT" parameters. Inthis example, subscriber 12 has an unrestricted terminating parameter(URT). Thus, the call terminating screening is passed (satisfied) sinceall calls via switch 28 are permitted to terminate at subscriber 12.

Since the call origination and termination restrictions are satisfied,switch 28 continues to proceed with the call setup to permit subscriber24 to communicate with subscriber 12. The IXC switch 28 transmits therequired call setup messages to central office switch 16 utilizingsignaling system 7. Similarly, central office switch 16 transmitsincoming call setup messages over trunks 18 to PBX 14 in order tocomplete the call to subscriber 12.

With regard to Call Scenario #1, it will be noted that the data storedas records in SCP database 34 for subscribers 24 and 12 constitute"complete" profiles for these end user subscribers. The complete profilemeans having all of the information for the subscribers that would beprovided if the subscriber was directly connected by a local loop/lineto the switch 28 instead of being connected by a trunk. This completeprofile information allows switch 28 to simulate a loop/line originationfrom a higher position in the network hierarchy than the central officeswitch which directly supports the subscriber. As used herein, a switchat a higher hierarchical level refers to a switch closer to the tollnetwork than another switch, i.e. a level further from the requestingsubscriber. The IXC switch 28, in addition to serving as a toll switchgateway or edge switch, also functions as a primary call originationswitch. The availability of complete profiles of the subscribers in LATA10 and the superior hierarchical position in the network permits switch28 to provide enhanced features and call origination functions tosubscribers in LATA 10 beyond the conventional features provided by thecentral office switches and PBXs in LATA 10. Since the IXC switch 28 hasa complete profile, it also has knowledge of signals which are relevantto each subscriber; for example, a flash-hook signal initiated bysubscriber 24 (or an equivalent ISDN/SS7 representation for a 3-Wayconference request if the originator utilizes an ISDN telephone) whichwas received by IXC switch 28 would be ignored since it has no meaning,that is, no features associated with subscriber 24 require a flash-hooksignal.

In the case where subscriber 20 originates a call to subscriber 12,since subscriber 20 is not part of a Centrex, e.g. Centrex 26,subscriber 20 may dial *10288+"called-digits" in order to place a callto subscriber 12. The "called-digits" would be a number that SCP 34could translate into the "true" number of subscriber 12, this numberbeing usable by IXC switch 28 and central office switch 16 for routingthe call. Alternatively, subscriber 20 may not even have to dial the*10288 if it has been provisioned as a preferred primary serviceprovider for subscriber 20 on central office switch 22. Central officeswitch 22 will then automatically process the call as if the subscriberhad dialed the *10288, or whatever access code that would route the callto IXC switch 28 for primary call origination services.

The process of handling a call from PBX supported subscriber 12 toCentrex supported subscriber 24 would follow similar steps. Subscriber12 would first dial an escape code to obtain a dial tone from centraloffice switch 16. Next, subscriber 12 would dial a further escape codethat would cause central office switch 16 to route the call over trunkgroup 30 with a request for primary call origination services from IXCswitch 28. The number of the called party would then be entered eitheras a complete directory number or an abbreviated dialing plan if such afeature is supported by IXC switch 28. The continuing processing byswitch 28 would generally follow that described above with access ofinformation from SCP database 34, call screening, and call terminationto the called party if allowed.

Thus, call origination services and features can be provided by an IXCswitch for calls originating via a PBX to a Centrex supported subscriberand for calls originating via Centrex equipment to a PBX supportedsubscriber.

Call Scenario #2

In this example, a person uses CPE 24 to place a call utilizing IXCswitch 28 to subscriber 12. This scenario is similar to Scenario #1except that the call originating person is a PIN user, i.e. seesubscriber PIN(X) in Table 1. The call originating person (COP) invokesthe call using CPE 24 the same way as explained in Scenario #1 exceptthat the COP enters PIN(X) before entering the abbreviated number forsubscriber 12. In this example, the COP's PIN is 998877665. It will beapparent to those skilled in the art that a special code or designatorsuch as the "*" or "#" can be utilized to identify the beginning, end orboth of the PIN. The use of the PIN permits IXC switch 28 to identifythe COP and utilize the features associated with the COP's record storedin SCP database 34 as identified by the PIN. In this example, the COP isa member of the MBGID of 10 and is also permitted to use 3-way callingas indicated in the features associated with PIN(X) as shown in Table 1.

In accordance with this illustrative example, IXC switch 28 utilizes thefeatures associated with the PIN of the COP as opposed to the featuresassociated with the directory number of the originating CPE 24 which wassent to the switch as part of the call setup request. However, it isalso envisioned that the features associated with the COP and CPE 24 canboth be retrieved by IXC switch 28 and effectively OR'ed to yield theequivalent of all features allowed to either the COP associated with thePIN or the features associated with the CPE 24. This alternativearrangement could be utilized to provide add-on features for people byassociating additional features with an assigned PIN.

The call setup from the COP utilizing CPE 24 to subscriber 12 isaccomplished substantially the same as indicated in Scenario #1 exceptthat the IXC switch 28 retrieves from SCP database 34 the recordassociated with the PIN (or both the PIN and subscriber 24 records inaccordance with the alternative embodiment). The call is then completedvia central office switch 16 and PBX 14 to subscriber 12.

In accordance with this illustrative example, the COP desires to add tothe existing call a third party, subscriber 20, which is not a member ofthe business group. The COP is authorized to originate calls to otherthan business group members since the COP has an unrestrictedorigination (UR0) feature as defined by the PIN(X) record in SCPdatabase 34 (see Table 1). Although subscriber 24 has an SRO feature, asopposed to the URO feature of the COP, the less restrictive URO featureassociated with the COP is utilized, thereby permitting call originationoutside the business group.

To initiate a 3-way call, the COP, during the established call withsubscriber 12, indicates a request for the 3-way call by a flash-hooksignal which is passed (e.g. as its equivalent ISDN/SS7 representationfor a 3-Way conference request) to IXC switch 28. Since a flash-hook ismeaningful with regard to a 3-way feature, and the 3-way feature is anassigned parameter in the record for the COP, the switch 28 responds byputting subscriber 12 on hold and provides dial tone to the COP. The COPenters the directory number for subscriber 20. Upon collecting thedirectory digits transmitted by the COP, the IXC switch 28 transmits aquery to the SCP database 34 seeking information, i.e. a record,corresponding to the entered directory number. Although subscriber 20 isnot a member of any business group, the COP has an URO parameter andhence, call origination screening provided by switch 28 is satisfied.The switch 28 then proceeds to transmit a call initiation request tocentral office switch 22 requesting a call be set up with subscriber 20.A communication link is then established between the COP at CPE 24 andthe subscriber 20. The entry of another flash-hook signal by the COP atCPE 24 is transmitted to IXC switch 28 which interprets the secondflash-hook as a request to complete the 3-way conference. The switch 28then releases the "held" call path to subscriber 12. Thus, the COP is insimultaneous communication with subscriber 20 and subscriber 12. It willbe apparent to those skilled in the art that the conference circuitneeded to satisfy the 3-way call requirements is provided by IXC switch28 since this switch provides the 3-way call service for such calls. Asan alternate to the IXC switch 28 directly providing the 3-way callrequirements, the IXC switch could direct (command) switch 22 to set upthe 3-way call and pass all needed parameters and data to switch 22.

This call scenario illustrates that a subscriber can utilize a PIN togain access to a predetermined set of call features that differ fromthose features assigned to the line being used to originate the call.This permits a member of a group to make calls to other members of thegroup from a CPE without predetermined group affiliation and withoutpredetermined call features. This allows a group member to retain thosecall features normally available to members.

Call Scenario #3

In this example, a call originating person (COP) places an interLATAcall origination at CPE 20 to subscriber 64. In accordance with thepresent invention, IXC switch 28 provides primary call processing forthe call originating in LATA 10 for a terminating party located in LATA54.

The beginning of this call is similar to that discussed in call scenario#2 in that the COP utilizes a CPE (CPE 20) to request service from IXCswitch 28 via central office switch 22 and trunk 32. The COP enters hisPIN (PIN(X) followed by subscriber 64's abbreviated BG number 8-1234.The IXC switch 28 utilizes the PIN to retrieve the corresponding recordfrom SCP database 34 which is stored in the IXC switch and used duringthe processing of the call. As will be seen from the subscriber recordassociated with PIN(X) in Table 1, the COP is associated with businessgroup MBGID=10. The abbreviated BG number entered by the COP forsubscriber 64, namely 8-1234, may not find an SCP 34 database recordwith features and CPE information for subscriber 64 since subscriber 64is not known in LATA 10. However, an SCP 34 database record will befound that allows translation of 8-1234 to a public routing number; thepublic routing number will be returned in the query response from SCP 34to IXC switch 28. Such a translation record could be part of a tablestored in SCP database 34 in which each row contains a MGBID groupnumber, a prefix or access code (e.g. "8" in abbreviated number 8-1234),and an area code (e.g. 214) and office code (e.g. 568) corresponding tothe prefix code. Thus, a public routing number can be derived based onthe record corresponding to the MGBID group number and access code.

IXC switch 28 will use the public routing number to route the callthrough the toll network to IXC switch 48. The originally dialedabbreviated number, 8-1234, will be preserved in some SS7 parameter,e.g. the access transport parameter (ATP), for use at IXC switch 48. TheCOP is granted permission to complete the interLATA MBG call to IXCswitch 48 since no terminating screening can be done at this time at IXCswitch 28. The PIN(X) subscriber's URO restriction will be carried inthe SS7 BG parameter to IXC switch 48 where originating and terminatingscreening will be done for the MBG call. Using the public routing numberreturned from SCP 34, IXC switch 28 and toll switches 38 . . . 40 routethe call to the terminating IXC switch 48. However, IXC switch 28includes additional information in the call setup message sent on theSS7 trunk 42 to toll switch 38 that includes the BG parameter indicatingthe business group, originating restrictions, terminating restriction ofthe calling party, an NSF parameter (also called hierarchical parameterherein) indicating that hierarchical services by the IXC switch(es) areto be provided for the call, and an ATP that contains the originallydialed abbreviated number. These pieces of information are in additionto other conventional call setup message information which will beforwarded in a conventional manner. The called party number, which isactually the public routing number used to route the call to IXC switch48, addresses IXC switch 48. This indicates to IXC switch 48 that switch48 is the terminating IXC switch for this call. The called number isreceived at IXC switch 48 along with the NSF and BG parameters, and theATP which carries the abbreviated number for subscriber 64. IXC switch48 interprets this information as requiring a query of SCP database 50for information concerning the abbreviated called party number(subscriber 64). This query is made in order to provide both callorigination and termination screening.

If the screening process permits the call, the IXC switch 48 forwardsthe required setup information to the associated central office switchwhich processes the termination of the call to the desired party.However, if the screening process fails, i.e. it is determined that theterminating party is not permitted to receive the call request, the IXCswitch gives the call originator appropriate terminating errortreatment, e.g. playing an error announcement to the call originator.

Referring to Table 1, the record associated with "214-568-1234", i.e.subscriber 64, is retrieved from SCP database 50. This data identifiesthe subscriber as being a member of business group 10 and that thesubscriber is SRT, meaning that the subscriber can receive calls via anIXC switch only from a business group member. However, since the COP isalso a member of the same business group, the call passes terminatingscreening. Since the originating restrictions for the COP are URO(carried in the SS7 BG parameter), the call passes call originatingrestrictions as well. Having passed call origination and calltermination restrictions, the call is further advanced by the IXC 48transmitting a call setup message to central office switch 56 andassociated Centrex equipment 62 which completes the call to subscriber64.

In accordance with this call scenario, the IXC switches 28 and 48support independent call origination screening and call terminationscreening. A subscriber can utilize a PIN to gain access to apredetermined set of call features for an interLATA call. This permits amember of a group to make calls to other members of the group from a CPEin another LATA and retain those features normally available to themembers.

Call Scenario #4

In this example a subscriber 12 of PBX 14 places an interLATA call tosubscriber 64 of Centrex services 62. Subscriber 12 dials some accesscode and the called number, e.g. *10-xxx-7/10 digits. The xxx is thecarrier ID (CIC) or service provider located at IXC switch 28 from whomsubscriber 12 wishes to obtain originating services. The *10-xxx is asignal (access code) to the local CO switch 16 that this call isrequesting "originating services" from the "xxx" service provider (e.g.AT&T or MCI) at IXC switch 28. CO switch 16 routes the call over trunk30 applying the appropriate signaling to let IXC switch 28 know thatthis is a call request for originating services. Such signaling to IXCswitch 28 could be as simple as the call coming in over a "dedicated"trunk 30, or having received an SS7 network specific facility (NSF)parameter for said service. It will also be understood that anabbreviated dialing plan could be used to identify the called partyinstead of the 7/10 digit called party number since the originatingparty will normally have abbreviated dialing as a supported PBX feature.

Upon receiving the call and signaling, IXC switch 28 is programmed toquery the SCP 34 database for the appropriate "xxx" (Carrier ID or CIC)for subscriber 12. Subscriber 12's ANI (calling party number) is alsoused at the IXC switch 28 for billing the call. IXC switch 28 isprogrammed to query the SCP 34 database for the appropriate serviceprovider "xxx" to obtain the calling party's information, e.g.information defining their allowed features and assigned terminalequipment. The retrieved information from SCP 34 identifies subscriber12 as being a member of business group 10 with URO and URT features;Table 1 shows the defined features. SCP 34 also provides the publicrouting number to IXC switch 28 so that the call can be routed to IXCswitch 48. Alternatively, an SCP database which is dedicated to oneservice provider would not require a query to locate the serviceprovider since the carrier in this case could be assumed.

SS7 signaling to IXC switch 48 includes information (e.g. an SS7 NSFparameter) identifying the call as one having requested originatingservices from an IXC switch. Additionally, the SS7 signaling conveys thebusiness group affiliation and the origination and terminationrestrictions associated with subscriber 12. This serves to cause IXCswitch 48 to query its SCP 50 database before terminating the call to alocal network, e.g. to trunk 58. IXC switch 48 retrieves informationfrom SCP 50 on the called party 64, e.g. subscriber 64's restrictions,if any. If IXC switch 48 and SCP 50 determine that the call can beallowed to complete, the call is advanced to CO switch 56 whichcompletes the call to subscriber 64. In this instance, the call isallowed to complete. Although subscriber 64 has an SRT restriction, itis satisfied since subscriber 12 has the same business groupaffiliation.

In this example, a PBX subscriber is allowed to use enhanced featureseven while making an interLATA call to a Centrex subscriber of the samebusiness group affiliation. Thus, neither the interLATA nature of thecall nor the mix of PBX and Centrex supported subscribers inhibited theuse of enhanced features.

General Information

The above examples illustrate that enhanced subscriber features need notbe restricted by limitations associated with the calling party'sequipment (PBX or Centrex) or local central office capabilities. Animportant aspect of this invention resides in recognizing and solvingthe problems which prevented members of affiliated groups from utilizingenhanced features that were available within their local equipment/LATAcommunity when making calls to other members of the group served bydifferent types of equipment or located in different LATAs.

It will be apparent that other variations of the uses of the aboveembodiments of the present invention can be made. For example, a1-800-xxx-yyyy number could be used in place of an access code as a wayof conveying a request to an IXC switch for call origination support.The IXC switch would receive this call request from a local centraloffice and, after querying its associated SCP database, would recognizethe 800 call request in combination with the calling party number as arequest for call origination support. In another aspect, a single setupmessage, which could be equivalent to a series of signals, could bereceived by the IXC switch containing all required signals andinformation needed to permit call origination services to be provided toa requesting subscriber.

In view of the above descriptions of embodiments, it will be apparentthat other call scenarios are supported by this invention. For example,a subscriber 12 of PBX 14 in LATA 10 can utilize call originationservices, such as abbreviated dialing, membership-based call screening,3-way conferencing, etc., provided by IXC switches 28 and 48 whencalling a subscriber 74 of PBX 70 in LATA 54. Similarly, Centrexsubscriber 24 served by a local switch 22 in LATA 10 can utilize callorigination services provided by IXC switches 28 and 48 when calling aCentrex subscriber 64 served by local switch 56 in LATA 54. Thus, callorigination services from an IXC switch can support PBX to PBX, PBX toCentrex, Centrex to PBX, and Centrex to Centrex calls as well as callsnot supported by either PBX or Centrex services.

Although embodiments of the invention have been described above, thescope of the invention is defined by the claims which follow.

                  TABLE 1                                                         ______________________________________                                        Subscriber   Features      CPE Type                                           ______________________________________                                        24           IDP1          Analog                                                          TGSR:         DTMF                                               312-713-1234 TGID = 05                                                                     SRO                                                                           URT                                                                           MGB:                                                                          MBGID = 10                                                       12           IDP1          Custom ISDN                                                     TGSR:                                                            708-979-1234 TGID = 06                                                                     URO                                                                           URT                                                                           MBG:                                                                          MBGID = 10                                                       20           Null          Analog                                             312-713-1235               DTMF                                               PIN (X)      IDP1          Null                                               998-877-665  MBG:                                                                          MBGID = 10                                                                    URO                                                                           URT                                                                           3-WAY                                                            64           IDP1          N-ISDN                                             214-568-1234 TGSR:                                                                         TGID = 15                                                                     SRO                                                                           SRT                                                                           MBG:                                                                          MBGID = 10                                                       60           Null          Analog                                             214-568-7981               DTMF                                               74           IDP1          Analog                                             214-979-3535 TGSR:         DTMF                                                            TGID = 12                                                                     URO                                                                           URT                                                                           MBG:                                                                          MBGID = 10                                                       ______________________________________                                    

The invention claimed is:
 1. In a telecommunication network having firstand second subscribers connected to first and second telecommunicationswitches, respectively, a method for providing call originationscreening of calls made by first subscribers to second subscriberscomprising the steps of:receiving, at a third switch disposed at ahierarchical level above the second switch, a call setup messagegenerated in response to a call request made by one of the firstsubscribers via the first switch, the call setup message including afirst group affiliation parameter defining one organization of which theone first subscriber is a member and a destination number of one of thesecond subscribers called by the one of the first subscribers, saidthird switch being capable of direct call origination services; locatinga first record in a first database coupled to the third switch inresponse to receiving the call setup message, the located first recordbased on the destination number contained in the call setup message;identifying a call screening parameter stored in said first record;making a determination of whether the call will be allowed to terminateto the one of the second subscribers based on a comparison of the callscreening parameter and the first group affiliation parameter, wherebycall screening is based on membership of the one of the firstsubscribers in the one organization.
 2. The method according to claim 1further comprising the step of locating a calling party record based onthe identity of the first subscriber in a second database coupled to afourth switch disposed at a hierarchical level above the first switch.3. The method according to claim 2 further comprising the step ofidentifying said first group affiliation parameter that is stored insaid calling party record.
 4. The method according to claim 2 furthercomprising the step of receiving a request for call origination servicesat the fourth switch from the first switch.
 5. The method according toclaim 2 further comprising the step of identifying in the seconddatabase an origination restriction parameter defining call originationrestrictions associated with the one of the first subscribers andincluding the origination restriction parameter in the call setupmessage sent to the third switch.
 6. The method according to claim 5wherein said making step further comprises the step of making adetermination of whether the call will be allowed to terminate to theone of the second subscribers based on a comparison of the callscreening parameter and the origination restriction parameter.
 7. Themethod according to claim 1 wherein the call screening parameteridentifies a predetermined set of affiliation parameters which allowincoming calls to terminate to the second subscriber only if the firstgroup affiliation parameter is included in said set of affiliationparameters.
 8. The method according to claim 1 wherein the call setupmessage further includes a hierarchy parameter indicative of callorigination services to be rendered by the hierarchical third switch,said locating step being responsive to receipt of the hierarchyparameter in the call setup message.
 9. In a telecommunication networkhaving first and second subscribers connected to first and secondtelecommunication switches, respectively, the improvementcomprising:means for receiving, at a third switch disposed at ahierarchical level above the second switch, a call setup messagegenerated in response to a call request made by one of the firstsubscribers via the first switch, the call setup message including afirst group affiliation parameter defining one organization of which theone first subscriber is a member and a destination number of one of thesecond subscribers called by the one of the first subscribers, saidthird switch being capable of direct call origination services; meansfor locating a first record in a first database coupled to the thirdswitch in response to receiving the call setup message, the locatedfirst record based on the destination number contained in the call setupmessage; means for identifying a call screening parameter stored in saidfirst record; means for making a determination of whether the call willbe allowed to terminate to the one of the second subscribers based on acomparison of the call screening parameter and the first groupaffiliation parameter, whereby call screening is based on membership ofthe one of the first subscribers in the one organization.
 10. Thenetwork according to claim 9 further comprising means for locating acalling party record based on the identity of the first subscriber in asecond database coupled to a fourth switch disposed at a hierarchicallevel above the first switch.
 11. The network according to claim 10further comprising means for identifying said first group affiliationparameter that is stored in said calling party record.
 12. The networkaccording to claim 10 further comprising means for receiving a requestfor call origination services at the fourth switch from the firstswitch.
 13. The network according to claim 10 further comprising meansfor identifying in the second database an origination restrictionparameter defining call origination restrictions associated with the oneof the first subscribers and including the origination restrictionparameter in the call setup message sent to the third switch.
 14. Thenetwork according to claim 13 wherein said making means furthercomprises making a determination of whether the call will be allowed toterminate to the one of the second subscribers based on a comparison ofthe call screening parameter and the origination restriction parameter.15. The network according to claim 9 wherein the call screeningparameter identifies a predetermined set of affiliation parameters whichallow incoming calls to terminate to the second subscriber only if thefirst group affiliation parameter is included in said set of affiliationparameters.
 16. The network according to claim 9 wherein the call setupmessage further includes a hierarchy parameter indicative of callorigination services to be rendered by the hierarchical third switch,said locating means being responsive to receipt of the hierarchyparameter in the call setup message.